Knife mechanism for tufting machines



Nov. 9, 1965 B. H. WITTLER 3,216,382

KNIFE MECHANISM FOR TUFTING MACHINES Filed March 21, 1963 i N V EN TOR. BER/VA RD H. WI TL ER BY WITNESS gum WC! 5 W X a ATTORNEY United States Patent Ofilice 3,216,382 Patented Nov. 9, 1965 3,216,382 KNIFE MECHANISM FOR TUFTING MACHINES Bernard H. Wittler, Rossville, Ga., assignor, by mesne assignments, to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Mar. 21, 1963, Ser. No. 266,931 Claims. (Cl. 112-79) The present invention relates to a knife mechanism for a tufting machine and particularly to a knife mechanism that is adapted for high speed operation.

In a conventional cut pile tufting machine there is provided a knife disposed on one face of the hook and having a cutting edge that cooperates with the edge at the underside of the loop seizing blade of the hook to sever the loops on the blade of the hook to form cut pile. In such a machine the knife is carried by an oscillating knife shaft that is parallel to the hook shaft, and the knife which is formed of spring steel, is arranged at a slight angle relative to the hook to insure cooperation between the cutting edges of the knife and hook. Upon operation of these machines, friction between the knife and hook generates a considerable amount of heat which limits the operating speed of the machine. When it is attempted to operate these machines at speeds in the neighborhood of 3,000 stitches per minute, the heat that it generated is so intense that the knife is destroyed within a few minutes.

Accordingly, it is an object of this invention to provide a knife mechanism that is capable of being operated successfully and continuously at high speeds, and at the same time, is simple and economical.

In accordance with this invention, the above objects have been attained by providing a knife that is disposed fiat against the one side face of the hook, thereby eliminating pressure points which tend to localize the generation of heat and thereby hasten destruction of the knife. At the same time, the knife is maintained against the side of the hook with suflicient force to insure cooperation between the cutting edges to sever the loops.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

FIG. 1 is a transverse sectional view of a tufting machine embodying the present invention.

FIG. 2 is a detail sectional view of the hook and knife mechanisms of the machine of FIG. 2.

FIG. 3 is a fragmentary sectional view taken substantially on the line 3-3 of FIG. 2.

FIG. 4 is a fragmentary exploded view in perspective of the hook and knife elements.

With reference to the drawings, there is illustrated a tufting machine having a frame 1 including a bed 2 and a head 3 overhanging the same. A backing fabric is adapted to be fed across the bed 2 by feed rolls including a let-off roll 4 and the take-up roll 5.

Mounted in the head 3 for endwise reciprocation is a push rod 6 carrying at its lower end a needle bar 7 which in turn carries the needle 8. Endwise reciprocation is imparted to the rod 6 by an eccentric 9 on the main shaft 10 of the machine, which eccentric is embraced by the strap end of a link 11 that is pivotally connected at its lower end to the rod 6. Yarn Y is fed to the needle 8 by yarn feed rolls 12.

Cooperating with the needle 8 is a hook 13 having a loop seizing blade 14 that is adapted to enter loops of yarn presented by the needle. The hook 13 includes a mounting portion 15 that is secured by a set screw 16 in a slot 17 in a hook bar 18 that is carried by the hook shaft 19. The hook shaft 19 is journaled in brackets 20 in the bed 2 and is adapted to be oscillated in timed relation to the reciprocation of the needle by drive connections (not shown) from the main shaft 10.

The hook 13 is arranged in the machine with the blade 14 extending in the direction opposite to the direction of feed of the base fabric so that the loops thereon are moved toward the closed end of the blade to where they are severed against the cutting edge 21 at the underside of the blade by the knife mechanism.

The knife mechanism comprises a knife shaft 22 journaled in the bed 2 by brackets 23 and oscillated by connections (not shown) from the main shaft 10. The knife shaft 22 is provided with a hole 24 that receives a stud 25 in a knife holder 26 and in which it is secured for endwise adjustment by a set screw 27. The knife holder 26 is substantially C-shaped in cross section and receives a knife-carrying element 28 that is secured therein for endwise adjustment by a set screw 29. Disposed between the end of the knife-carrying element 28 and the hook 13 is a short knife 30 having a cutting edge 31 that cooperates with the cutting edge 21 of the hook to sever the loops. The knife is coupled to the knife-carrying element 28 by a lug 32 on the face of the knife 30 which is received within a complemental aperture 33 in the knife-carrying element 28. The knife is biased against the face of the hook 13 by the knife-carrying element 28 which is resilient, preferably of spring steel, and is disposed at a slight angle to or in other words leans toward the hook, the end of the knife-carrying element 28 being bent away from the hook so that there is substantially an arcuate portion of the element 28 opposite the knife and thus a line contact between the knife and knife-carrying element, as at 34, FIG. 3. The line 34 is arranged substantially through the center of the lug 32, which is disposed in the area opposite the face of the hook 13. In this manner, the knife 30 is coupled to the knife-carrying element 28 and is oscillated therewith upon oscillation of the knife shaft 22 to impart loop severing actuation to the knife. At the same time, the knife is free to float relative to the knife-carrying element 28, or in other words, to move about an axis normal to the hook so that under the bias of the knife-carrying element 28, it will remain fiat against the face of the hook. The cutting edges 31 and 21 are thereby maintained in cooperative relation and there are no pressure points which, upon relative movement of the hook and knife, would tend to overheat. Whatever heat is generated between the hook and knife is spread over a larger area and is more readily dissipated, thus holding the temperature of the elements to an acceptable level.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Having thus described the nature of the invention, what I claim herein is:

1. In a tufting machine having an endwise-movable needle adapted to penetrate a backing fabric and to project a loop of yarn therethrough, a hook having a loop seizing blade adapted to enter a loop of yarn presented by said needle, and a knife mechanism cooperating with said hook to sever loops thereon to form cut pile, said knife mechanism comprising a knife disposed in abutment with said hook, a knife-carrying element contacting said knife on the opposite side of said knife from said hook and biasing said knife in abutment with said hook, means coupling said knife to said knife-carrying element for imparting loop severing actuation to said knife upon actuation of said knife-carrying element and for floating relative to said knife-carrying element about an axis in a direction normal to the face of said hook to provide for seating of said knife flat upon the face of said hook.

2. In a tufting machine having an endwise movable needle adapted to penetrate a backing fabric and to project a loop of yarn therethrough, a hook having a loop seizing blade adapted to enter a loop of yarn presented by said needle, and a knife mechanism cooperating with said hook to sever loops thereon to form cu-t pile, said knife mechanism comprising a knife disposed in abutment with said hook, a knife-carrying element contacting said knife on the opposite side of said knife from said hook, said knife-carrying element being resilient and being arranged to bias said knife into abutment With said hook, means coupling said knife to said knifecarrying element for imparting loop severing actuation to said knife upon actuation of said knife-carrying element and for floating relative to said knife-carrying element about an axis in a direction normal to the face of said hook to provide for seating of said knife flat upon the face of said hook. v

3. In a tufting machine in accordance with claim 2 wherein said knife-carrying element is inclined relative to said hook and the end thereof is bent away from said hook whereby said knife-carrying element engages said knife substantially along a line of contact.

4. In a tufting machine in accordance with claim 2 wherein said means for coupling said knife to said knifecarrying element comprises on said knife-carrying element and knife a lug and a complemental aperture for receiving said lug.

5. In a tufting machine in accordance with claim 4 wherein said lug is formed on said knife and said aperture is formed in said knife-carrying element.

References Cited by the Examiner UNITED STATES PATENTS 2,143,679 1/39 Baggett et al. 112-79 2,242,103 5/41 Borenstein et a1. 112-79 2,330,615 9/43 Parker 112-79 3,084,645 4/63 Card 112- 79 JORDAN FRANKLIN, Primary Examiner. 

1. IN A TUFTING MACHINE HAVING AN ENDWISE-MOVABLE NEEDLE ADAPTED TO PENETRATE A BACKING FABRIC AND TO PROJECT A LOOP OF YARN THERETHROUGH, A HOOK HAVING A LOOP SEIZING BLADE ADAPTED TO ENTER A LOOP OF YARN PRESENTED BY SAID NEEDLE, AND A KNIFE MECHANISM COOPERATING WITH SAID HOOK TO SEVER LOOPS THEREON TO FORM CUT PILE, SAID KNIFE MECHANISM COMPRISING A KNIFE DISPOSED I N ABUTMENT WITH SAID HOOK, A KNIFE-CARRYING ELEMENT CONTACTING SAID KNIFE ON THE OPPOSITE SIDE OF SID KNIFE FROM SAID HOOK AND BIASING SAID KNIFE IN ABUTMENT WITH SAID HOOK, MEANS COUPLING SAID KNIFE TO SAID KNIFE-CARRYING ELEMENT FOR IMPARTING LOOP SEVERING ACTUATION TO SAID KNIFE UPON ACTUATION OF SAID KNIFE-CARRYING ELEMENT ABOUT AN AXIS IN RELATIVE TO SAID KNIE-CARRYING ELEMENT ABOUT AN AXIS IN A DIRECTION NORMAL TO THE FACE OF SAID HOOK TO PROVIDE FOR SEATING OF SAID KNIFE FLAT UPON THE FACE OF SAID HOOK. 